That "first things first" was the first clue that you were the killer. Your proof that Trucks wasn't the killer was my second.
I know you looked through the scenarios and tried to guess who would be the best "lie", but you should have thought also about telling the truth. Had you said that you targeted FF due to my reasoning on day 2, you probably would have made me second guess trucks. In your lie, you cleared a townie to me, that was your second mistake.